1. Field of the Invention
The present invention relates to new type dicing tape, comprising polyimide-based dicing tape which can be adhesively attached to a silicon wafer and diced at near room temperature, and can function as an adhesive for laminating diced individual silicon wafers onto circuit boards.
2. Description of Related Art
Conventionally, semiconductor wafers such as silicon wafers are manufactured in large-diameter disc shapes, and then for example, a circuit pattern is formed on the surface thereof, protective tape is attached to one surface to protect the circuit pattern and the back side is then machined for thinning, after which, in order to form semiconductor chips from the machined semiconductor wafer, the semiconductor manufactured in the large-diameter disc shape is adhered to a ring frame via adhesive tape and then cut (diced) into multiple dice-shaped (square) or rectangular chips. The individual cut chips are subsequently separated from the adhesive tape and the separated chips are successively bonded to, for example, the inner leads of device holes on IC mounting boards.
Such adhesive tape is referred to as dicing tape, and for dicing, one surface is laminated by adhesive force onto a large-diameter disc-shaped silicon wafer while a release film is laminated on the back side, while after dicing, the individual silicon wafers are attached to substrates via adhesive tape (dicing tape) which has been cut to the prescribed size, and these are post-processed by wire bonding, mold sealing, solder ball formation or the like to manufacture semiconductor packages.
For example, Japanese Unexamined Patent Publication No. 10-324857 describes adhesive tape for use as dicing tape. However, the adhesive tape described in this publication is composed of an adhesive composition of (meth)acrylic acid copolymer and phenol resin, which is unsuitable for high-density mounting.
Polyimide-based dicing tape has therefore been investigated, but polyimide-based dicing tape has been associated with disadvantages in terms of process steps, because of its low tacky strength (initial adhesive strength) at low temperatures of around room temperature, such that a higher ambient temperature is required to increase the adhesive force which thus necessitates supplementary heating equipment.